Light bars or emergency lights of the type used on emergency vehicles such as fire trucks, police cars, and ambulances, utilize warning signal lights to produce a variety of light signals. These light signals involve the use of various colors and patterns. Generally, these warning signal lights consist of incandescent and halogen light sources having reflective back support members and colored filters.
Many problems exist with the known methods for producing warning light signals. One particular problem with known light sources is their reliance on mechanical components to revolve or oscillate the lamps to produce the desired light signal. Additionally, these components increase the size of the light bar or emergency lights which may adversely affect the vehicles aerodynamic characteristics. Moreover, there is an increased likelihood that a breakdown of the light bar or light source will occur requiring the repair or replacement of the defective component. Finally, the known light bars and sources require a relatively large amount of electrical current during operation. The demands upon the electrical power system for a vehicle may therefore exceed available electrical resources reducing optimization of performance.
The most common light sources being used in light bars or emergency lights include halogen lamps or gaseous discharge xenon lamps. These lamps emanate large amounts of heat which is difficult to dissipate from a sealed light enclosure or emergency light and which may damage the electronic circuitry contained therein. In addition, these lamps consume large amounts of current requiring a large power supply or large battery or electrical source which may be especially problematic for use with a vehicle. These lamps also generate substantial electromagnetic emissions which may interfere with radio communications for a vehicle. Finally, these lamps, which are not rugged, have relatively short life cycles necessitating frequent replacement.
Another problem with the known warning signal lights is the use of filters to produce a desired color. Filtering techniques produce more heat that must be dissipated. Moreover, changing the color of a light source requires the physical removal of the filter from the light source or emergency light and the insertion of a new filter. Furthermore, filters fade or flake over time rendering the filters unable to consistently produce a desired color for observation in an emergency situation.
These problems associated with traditional signaling lamps are exacerbated by the fact that creating multiple light signals requires multiple signaling lamps. Further, there is little flexibility in modifying the light signal created by a lamp. For example, changing a stationary lamp into one that rotates or oscillates would require a substantial modification to the light bar which may not be physically or economically possible.
The present invention generally relates to electrical lamps and to high brightness light-emitting diode or “LED” technology which operates to replace gaseous discharge or incandescent lamps as used as automotive warning signal light sources.
Illumination lamps for automobile turn signals, brake lights, back-up lights, and/or marker lights/headlights frequently have accompanying utility parabolic lens/reflector enclosures which have been used for utility warning signals or emergency vehicle traffic signaling.
These signaling devices as known are commonly referred to as “unmarked corner tubes,” or “dome tubes. These signaling devices as known frequently utilize xenon gaseous discharge tubes or incandescent lamps as the illumination sources.
A problem with the prior art is the cost and failure rate of the known “unmarked corner tubes,” or “dome lights.” The failure rate of these devices frequently results in a significant amount of “down time” for a vehicle to effectuate replacement. Further, an officer is frequently unaware that a vehicle light is inoperative requiring replacement. This condition reduces the safety to an officer during the performance of his or her duties. In addition, the reduced life cycle and failure rate of the known illumination devices significantly increases operational costs associated with material replacement and labor. A need, therefore, exists to enhance the durability, and to reduce the failure rate, of illumination devices while simultaneously reducing the cost of a replacement illumination source.
In the past, the xenon gaseous discharge lamps have utilized a sealed compartment, usually a gas tube, which may have been filled with a particular gas known to have good illuminating characteristics. One such gas used for this purpose was xenon gas, which provides illumination when it becomes ionized by the appropriate voltage application. Xenon gas discharge lamps are used in the automotive industry to provide high intensity lighting and are used on emergency vehicles to provide a visible emergency signal light.
A xenon gas discharge lamp usually comprises a gas-filled tube which has an anode element at one end and a cathode element at the other end, with both ends of the tube sealed. The anode and cathode elements each have an electrical conductor attached, which passes through the sealed gas end of the lamp exterior. An ionizing trigger wire is typically wound in a helical manner about the exterior of the glass tube, and this wire is connected to a high voltage power source typically on the order of 10–12 kilowatts (kw). The anode and cathode connections are connected to a lower level voltage source which is sufficient to maintain illumination of the lamp once the interior gas has been ionized by the high voltage source. The gas remains ignited until the anode/cathode voltage is removed; and once the gas ionization is stopped, the lamp may be ignited again by reapplying the anode/cathode voltage and reapplying the high voltage to the trigger wire via a voltage pulse.
Xenon gas lamps are frequently made from glass tubes which are formed into semicircular loops to increase the relative light intensity from the lamp while maintaining a relatively small form factor. These lamps generate extremely high heat intensity, and therefore, require positioning of the lamps so as to not cause heat buildup in nearby components. The glass tube of a xenon lamp is usually mounted on a light-based pedestal which is sized to fit into an opening in the light fixture and to hold the heat generating tube surface in a light fixture compartment which is separated from other interior compartment surfaces or components. In a vehicle application, the light and base pedestal are typically sized to fit through an opening in the light fixture which is about 1 inch in diameter. The light fixture component may have a glass or plastic cover made from colored material so as to produce a colored lighting effect when the lamp is ignited. Xenon gas discharge lamps naturally produce white light, which may be modified to produce a colored light, of lesser intensity, by placing the xenon lamp in a fixture having a colored lens. The glass tube of the xenon lamp may also be painted or otherwise colored to produce a similar result, although the light illumination from the tube tends to dominate the coloring; and the light may actually have a colored tint appearance rather than a solid colored light. The color blue is particularly hard to produce in this manner.
Because a preferred use of xenon lamps is in connection with emergency vehicles, it is particularly important that the lamp be capable of producing intense coloring associated with emergency vehicles, i.e., red, blue, amber, green, and clear.
When xenon lamps are mounted in vehicles, some care must be taken to reduce the corroding effects of water and various chemicals, including road salt, which might contaminate the light fixture. Corrosive effects may destroy the trigger wire and the wire contacts leading to the anode and cathode. Corrosion is enhanced because of the high heat generating characteristics of the lamp which may heat the air inside the lamp fixture when the lamp is in use, and this heated air may condense when the lamp is off resulting in moisture buildup inside the fixture. The buildup of moisture may result in the shorting out of the electrical wires and degrade the performance of the emission wire, sometimes preventing proper ionization of the gas within the xenon gas discharge lamp.
Warning lights, due to the type of light source utilized, may be relatively large in size which in turn may have an adverse affect upon adjacent operational components. In addition, there is an increased likelihood for a breakdown of the light source requiring repair or replacement of components.
Another problem with the known warning signal lights is the use of rotational and/or oscillating mechanisms which are utilized to impart a rotational or oscillating movement to a light source for observation during emergency situations. These mechanical devices are frequently cumbersome and difficult to incorporate and couple onto various locations about a vehicle due to the size of the device. These mechanical devices also frequently require a relatively large power supply to engage and operate the device to impart rotational and/or oscillating movement for a light source. Power consumption of electrical components for an emergency vehicle is of primary consideration for vehicle operators.
Another problem with the known warning signal lights is the absence of flexibility for the provision of variable intensity for the light sources to increase the number of available distinct and independent visual light effects. In certain situations it may be desirable to provide a variable intensity for a light signal or a modulated intensity for a light signal to provide a unique light effect to facilitate observation by an individual. In addition, the provision of a variable or modulated intensity for a light signal may further enhance the ability to provide a unique desired light effect for observation by an individual.
No warning lights are known which are flexible and which utilize a variable light intensity to modify a standard lighting effect. The warning lights as known are generally limited to a flashing light signal. Alternatively, other warning signal lights may provide a sequential illumination of light sources. No warning or utility light signals are known which simultaneously provide for modulated and/or variable power intensity for a known type of light signal to create a unique and desirable type of lighting effect.
No warning signal lights are known which provide an irregular or random light intensity to a warning signal light to provide a desired lighting effect. Also, no warning light signals are known which provide a regular pattern of variable or modulated light intensity for a warning signal light to provide a desired type of lighting effect. Further, no warning light signals are known which combine a desired type of light effect with either irregular variable light intensity or regular modulated light intensity to provide a unique and desired combination lighting effect.
It has also not been known to provide alternative colored LED light sources which may be electrically controlled for the provision of any desired pattern of light signal such as flashing, pulsating, oscillating, modulating, rotational, alternating, strobe, and/or combination light effects. In this regard, a need exists to provide a spatially and electrically efficient LED light source for use on an emergency or utility vehicle which provides the appearance of rotation or other types of light signals without the necessity of a mechanical devices. In addition, a need exists to provide a spatially and electrically efficient LED light source for use on an emergency vehicle which provides a flashing, modulated, oscillating, rotational, alternating, and/or strobe light effects without the necessity of mechanical devices.
In view of the above, there is a need for a warning signal light that:                (1) Is capable of producing multiple light signals;        (2) Produces the appearance of a revolving or oscillating light signal without relying upon mechanical components;        (3) Generates little heat;        (4) Uses substantially less electrical current;        (5) Produces significantly reduced amounts of electromagnetic emissions;        (6) Is rugged and has a long life cycle;        (7) Produces a truer light output color without the use of filters;        (8) Is positionable at a variety of locations about an emergency vehicle; and        (9) Provides variable power intensity to the light source without adversely affecting the vehicle operator's ability to observe objects while seated within the interior of the vehicle.        
Other problems associated with the known warning signal lights relate to the restricted positioning on a vehicle due to the size and shape of the light source. In the past, light sources due to the relatively large size of light bars or light sources, were required to be placed on the roof of a vehicle or at a location which did not interfere with, or obstruct, an operator's ability to visualize objects while seated in the interior of the vehicle. Light bars or light sources generally extended perpendicular to the longitudinal axis of a vehicle and were therefore more difficult to observe from the sides by an individual.
The ease of visualization of an emergency vehicle is a primary concern to emergency personnel regardless of the location of the observer. In the past, optimal observation of emergency lights has occurred when an individual was either directly in front of, or behind, an emergency vehicle. Observation from the sides, or at an acute angle relative to the sides, frequently resulted in reduced observation of emergency lights during an emergency situation. A need therefore exists to improve the observation of emergency lights for a vehicle regardless of the location of the observer. A need also exists to improve the flexibility of placement of emergency lights upon a vehicle for observation by individuals during emergency situations.
In the past, flashing light signals emanating from light bars have been used to signal the presence of an emergency situation necessitating caution. A need exists to reduce the size of light sources on an emergency vehicle and to improve the efficiency of the light sources particularly with respect to current draw and reduced aerodynamic drag. A need also exists to enhance the flexibility of positioning of light sources about a vehicle for observation by individuals. In order to satisfy these and other needs, more spatially efficient light sources such as LED's are required. It is also necessary to provide alternative colored LED light sources which may be electrically controlled for the provision of any desired pattern of light signal such as flashing, alternating, pulsating, oscillating, modulating, rotational, and/or strobe light effects without the necessity of spatially inefficient and bulky mechanical devices. In that regard, a need exists to provide a spatially and electrically efficient LED light source for use on an emergency vehicle which provides any of the above-identified types of warning light signals without the necessity of mechanical devices. In addition, a need exists to provide a spatially and electrically efficient LED light source for use on an emergency vehicle which provides a flashing, alternating, pulsating, rotating, modulated, oscillating, and/or strobe light effect or combinations thereof without the necessity of mechanical devices.